Musculoskeletal disorders account for significant dysfunction in the American population. However, estimating the impact of musculoskeletal diseases upon the health status of Americans has been difficult. Current estimates are problematic for at least three reasons. First, estimates from the National Health Interview Survey (NHIS) depend upon self-reports in response to a list of conditions, and there is no verification that those who report arthritis are actually afflicted by these problems. Second, these reports are in response to a one-sixth sample list, meaning that five-sixths of the sampled population do not receive the inquiry about arthritis. Third, reports of dysfunction are not validated against actual observations of dysfunction. A forth problem is that the dysfunction categories captured by the National Health Interview Survey cannot be easily translated into units that are clearly understood by policy makers. The Health Objectives for the Nation, Year 2000, include the requirement for estimating health status using well-years. These measures are scheduled to be included in the National Survey beginning in 1991 or 1992. We propose to evaluate the validity of reports of arthritis and arthritis- related dysfunction for 250 adults by comparing responses to the survey with (1) physical examinations by a rheumatologist and (2) an Internal Consistency Analysis of their responses to QWB questions. In the second phase of the project, a separate sample of 200 adults with arthritis will be given the Quality of Well-being Scale and other NHIS questions. They will then be asked to perform a variety of activities under observation. These observations, and in Internal Consistency Analysis of their responses to the NHIS and Quality of Well-being (QWB) questions, will each be used to estimate the extent to which dysfunction is captured by the survey questions. The third and most important phase of the research will use data from the National Health Interview Survey in order to estimate the number of well-years of life lost due to musculoskeletal disorders. Data for the survey will be analyzed using a variety of multivariate techniques with adjustment for covariates. Reports from the study will be made available to public health policy makers. These studies should provide substantial information about the impact of musculoskeletal diseases in comparison to other diseases that affect the American population.